1. Field of the Invention
The present invention pertains to an image input device such as an electronic still camera or image reader, in which image data obtained by sensing an image is provided to an external device by means of an output interface.
2. Description of the Prior Art
Various types of image input devices have been conventionally used to receive an image of an object or text and to convert it into image data. For example, in order to sense the still image of a person or scenery, electronic still cameras having built-in CCD sensors are used. An electronic still camera outputs, or downloads, image data obtained through image sensing to a TV monitor, personal computer, etc., such that the sensed image may be displayed on the screen or printed. Image readers are used to sense the image of text. An image reader outputs image data obtained through image sensing to an image processing device such as a high precision color printer or workstation, such that the sensed image may be printed or stored in a memory device.
In a conventional image input device as described above, the conditions used for image sensing are fixed. For example, in an electronic still camera, the resolution is determined by the number of the pixels of the CCD sensor and image sensing is performed using that resolution, i.e., the maximum resolution.
However, external devices that are connected to an image input device vary in resolution. For example, a high precision color printer has 5,000.times.8,000 pixels, while a standard color printer has 2,000.times.3,000 pixels and a TV monitor has 500.times.800 pixels. In this way, the resolution varies from one external device to another.
An image input device needs to output image data that has a resolution matching the resolution of the external device connected to it. If an external device is connected that has a resolution different from that of the image data obtained through image sensing, a process to convert the resolution must take place inside the image input device. Because such a conversion process requires time, the overall processing speed decreases to the same extent. Furthermore, where the resolution is to be increased, for example, the image data needs to be increased using approximation, which gives rise to the problem that errors are included in the image data.
The present invention addresses these problems. Its object is to provide an image input device in which conversion of resolution is not necessary or is made as simple as possible when image data is output to an external device.